This disclosure sets forth an improved diaphragm valve. It is a valve which controllably switches a set of multiple ports. Indeed, it can operate with any number of ports, and the typical preferred number is 6, 8, 10 or 12 ports. Examples using many ports will be illustrated further. In operation, it is a valve which switches between two positions where operation changes two sets of ports in timed operation.
The valve is constructed with an upper cylinder head, a central cylinder body, and a lower cylinder head. The upper and lower heads are joined to the cylinder body by threaded members which are aligned by threading into a common tapped opening through the cylinder body. This aligns the upper and lower heads with the same or common axis, and it also aligns both heads so that they can be pulled together with independent control of tensioning of the two heads. Pressure responsive pistons are located so that fluid introduced under pressure operates the device. In the preferred version, there are two pistons which are responsive to pressure, the two pistons moving so that the ports are collectively opened and switched dependent on the application of pressure. In that sense, the valve is a binary control device.
The valve uses a diaphragm located at one face of the cylinder and upper head, and is switched so that a flow path adjacent to the diaphragm is controlled. The diaphragm is circular with a bead defining a circular flow path when assembled between the head and cylinder. This bead is clamped shut at selected locations by a number of push rods. In this embodiment, the push rods bear against the diaphragm and upper head from the cylinder. Preferably, the push rods are formed of a compressible resilient material so that precise manufacturing of the push rods is not required, thereby accommodating variations in push rod length. Moreover, the push rods bear against the diaphragm so that the diaphragm is compressed ever so slightly to provide the appropriate flow control. Leakage along the face of the diaphragm is prevented by applying an adequate and sufficient sealing force between the upper head and cylinder. This clamps the diaphragm in place and forms a peripheral seal around the diaphragm. It forms a facial seal in the region of the bead also. The bead formed in the diaphragm is confined so that the push rods bear against the diaphragm from the bottom side, thereby closing the bead and switching the fluid path for the ports in the valve.
In the preferred embodiment, the device is manufactured with N ports where N is a whole number, even integer. The push rods are divided into two sets and are alternated so that there are N push rods and they are spaced approximately between the two ports nearer to each push rod. This enables them to close the diaphragm flow path as will be defined. Moreover, this enables the push rods to bear against the bottom side of the diaphragm in a timed fashion so that first one set and then a second set of push rods is operated. The push rods are alternated so that proper valving action can be obtained. This involves operating alternate push rods with one piston and the remaining set of push rods with the other piston. More will be noted regarding the push rod operation so that the ports are switched under push rod control.
When no pressure is applied to the diaphragm valve, half of the push rods are forced upwardly against the diaphragm. This movement is accomplished by a bias spring. The bias spring is overcome by the application of fluid pressure. This pressure forces a pair of pistons apart, and reverses the state of the push rods so that half the push rods are retracted and the other half are extended. This accomplishes valves switching. As will be understood, push rod travel is relatively short, typically in the range of perhaps 0.002 to about 0.006 inches. Since this range of travel is quite short, the push rods provide sharp movement so that the switching interval is very brief. As one set of rods is retracted, the other is extended against the diaphragm.
One advantage of the present apparatus is the incorporation of a single tension point. A threaded bolt is positioned in each head and the bolts are aligned centrally of the cylinder. This is easier to assemble. It does not pose the problem of applying controlled torque to a set of head bolts around the structure. This assures uniform pressure applied around the periphery of the diaphragm and on the face of the diaphragm so that proper sealing is accomplished. Moreover, sealing to close the gap between the head and cylinder is accomplished uniformly when a single centralized bolt is tightened. This mode of assembly is highly desirable and provides the requisite tension for the clamping action on assembly. The device is also adjustable with regard to operating pressure. By utilization of different springs, the operation pressure can be changed. The system typically operates with a control pressure which is quite low such as 5 or 10 psi and a second pressure which is relatively high such as 1000 psi. Again, the gap between the two pressures can be modified, and the maximum pressure can be changed so that switching occurs at some different pressure.
Summarizing the present disclosure, it is a diaphragm valve which is assembled with a housing having a central cylindrical body with upper and lower heads attached to it. The body is axially drilled with a threaded passage, and each head is attached by means of a single bolt. The bolts are cut to a length so that they do not jam in the threaded passage. There is sufficient space left between the two bolts to enable threading together with controlled tension in each bolt. The diaphragm is clamped between the upper head and cylinder. In the preferred version, the diaphragm is formed of resilient material and has a shaped bead in it which encircles the ports in the upper head. The bead defines a flow path which connects all the ports on a common header until the spaces between ports are closed by raising a set of push rods. Since the device includes N ports, it also uses N push rods where the push rods are divided into two sets, the two sets of push rods being alternately deployed and alternately operated by a pair of pistons enclosed within the cylinder.